1. Field of the Invention
The present invention relates generally to a variable damping force shock absorber for an automotive suspension system. More specifically, the invention relates to a variable damping shock absorber which can adjust damping characteristics for bounding stroke motion and damping characteristics for rebounding motion independent of each other.
2. Description of the Background Art
A of typical construction a variable damping force shock absorber has been disclosed in Japanese Patent First (unexamined) Publication (Tokkai) Showa 58-77943. The variable damping force shock absorber has a damping characteristics adjusting mechanism which adjusts damping characteristic of the shock absorber irrespective of the stroke direction. Such prior proposed variable damping force shock absorber is not yet complete for achieving satisfactorily level of riding comfort and vehicular driving stability.
Namely, as can be appreciated, the optimal damping characteristics of the bounding motion and rebounding motion is necessaily different from each other in most vibration modes. Therefore, in setting damping guidelines of common damping characteristics both for the bounding motion and the rebounding motion, difficulty arises to determined the optimal damping characteristics both for the bounding motion and rebounding motion, since the optimal damping characteristics for one of the bounding and rebounding motions cannot be the optimal damping characteristics for the other direction of motion. In other words, as long as the common damping characteristics for the bounding and the rebounding motion is to be set, the set damping characteristics can not be optimal for both the bounding and the rebounding motion.